qgis - in a single vector layer I have a three of polygons with different field values (e.g1,2,3). How Can I color each field value polygon differently?

In a single vector layer I have a three of polygons with different field values (e.g1,2,3). How Can I color each field value polygon differently? To explain a bit more my three polygons are showing the levels of risks. I would like to demonstrate red color where ever the polygon field value is 3 and blue where is one.

I can show the polygons field attribute value (number as text) on the map using labels but can not use the value to illustrate different color for each field attribute value.